CFD analysis of the dispersed phase behavior for micropowders production via spray drying and ultrasonic atomization

Abstract

This work is devoted to the use of modern computer simulation tools based on the principles and methods of computational fluid dynamics that are applied to develop processes and equipment for producing spray dried micropowders. The feed solution was atomized into small droplets using an ultrasonic nozzle that exploits the principle of liquid disintegration caused by impact of high-frequency wave oscillations. The use of this device for spraying a liquid allowed obtaining spherical particles with diameters less than 20?μm and with a narrow size distribution. The process development is based on a mathematical model incorporating the hydrodynamics, heat and mass transfer mechanisms, which has been formulated to numerically predict particles trajectories and temporal changes of their mass and temperatures. The generated data were used to analyze the trajectories of discrete phase particles considering various process parameters and to estimate adhesion of wet particles to the drying chamber and nozzle. Also, predicted were the degree of particles deposition and precipitation in a cyclone, since these are useful for selection of process parameters to ensure maximum quality of particles and maximum attainable efficiency of the system collecting finished products.